Current Efficiency and Mechanisms of Redox Reaction of Iron at the Interface between Solid Iron and Molten Slags

Abstract

The electrode of solid Fe/40CaO-40SiO₂-20Al₂O₃ (mass%) molten slag with 0.55-10 mass% of total iron oxide were electrolyzed in Ar at 1 573 K, using Pt-air/ZrO₂-9mol%MgO electrode as a reference electrode. The current efficiency of the reaction of Fe=Fe²⁺+2e was 1.0 for anodic overvoltage less than 200 mV and gradually decreased to 0.67 at 600 mV. The efficiency was zero for cathodic overvoltage until –600 mV. From the electrochemical analysis of the redox reaction of iron, it was concluded that the anodic reaction was the oxidation of iron to Fe²⁺ up to 200 mV and was accompanied by the oxidation of Fe²⁺ to Fe³⁺ above 200 mV. The cathodic reaction was the reduction of oxygen dissolved in molten slag.